REFLECTOR: Cabin Heating

Wed, 28 Jan 2004 00:16:50 -0600

I tried more or less the same thing.  Since the air passing through the oil
cooler only has a fraction of a second to absorb heat, I reasoned that if I
slowed the airflow then more heat would be absorbed.  With the rear cooler,
in the winter, cooling the oil should not be a problem.  I built a small
"plenum" to install in front of the oil cooler.  It is about an inch deep,
covering the cooler inlet.  It has several 5/16" holes drilled in the side
facing the airflow.  Well, it didn't work at all.  It did cut the airflow
going through the cooler core, but it didn't seem much warmer, just less of
it.
   I got the best results from sealing up all of the air leaks that I could.
What helped the most was forming a silicon gasket on one of the nose gear
doors to close up the gap between the doors when closed.
   Still looking for more heat.

Dave Scharfenberg
std/rg

on 1/27/04 8:19 AM, Chuck Jensen at cjensen@dts9000.com wrote:

> Since every configuration is different, yours may vary but I tried some of
> your proposed fixes with less than stellar results. My cabin air is fed from
> a flapper that opens and taps air flow downstream plenum of the front oil
> cooler and ducts it to the cabin.  It was obvious, due to the massive
> airflow thru the oil cooler, the outlet discharge air was heated just a few
> degrees.  Figuring that by slowing the air flow, the increased residence
> time would allow sufficient heating of the air, I cut some squares of a
> cloth bag filter and put 4 layers over the cooler inlet and plugged the
> plenum outlet.  The only air allowed to pass was what I feed to the cabin.
> My plan was to rely on the rear oil cooler to maintain engine oil temps.
> 
> On the test flight at OAT 5C, the cabin heat was nice and toasty; a big
> improvements (and a high "smug" factor).  Then the oil temps started to
> climb, and climb.  Finally topping out at 220C (181C is normal) and elevated
> CHTs at reduced cruise.  End of experiment.  Removed the outlet plug and 2
> of the 4 cloth layers on the inlet and went back to freezing at 0C OAT.  It
> was unexpected (in my mind) that the front oil cooler carried that large a
> fraction of the cooling load.  I expected to be able to block off the front
> cooler and still maintain adequate oil temperatures. Not. There just doesn't
> seem to be a happy medium.
> 
> Bottom line; I'm going to try a second oil cooler, in series with the front
> cooler, that's dedicated solely to cabin heat.
> 
> Chuck
> 
> Jim S. wrote:
> 
> I have the same problem with my 173 FG.  I have outlets to the cabin in the
> outlet
> plenum of the forward oil cooler, but not much air goes there if it can get
> out the
> bottom scoop.  I plan on making a "flapper valve" that in one position
> covers the
> outlets to the cabin, and in the other position covers the overboard vent.
> That will
> force all the air coming through the forward cooler into the cabin.  Of
> course that's
> continually heating outside air, so if it still doesn't work, I'll fix it so
> when I
> open the vents to the cabin and close the overboard vent, it will also close
> off the
> inlet and turn on a blower that recirculates cabin air through the forward
> cooler.
> I'm not worried about not being able to cool the oil since this only happens
> in the
> dead of winter when the aft cooler should be able to do the job by itself.
> Fix it next summer, try it next winter .... Jim S.
> 
> Chuck Jensen wrote:
> 
>> Jack,
>> 
>> I get the same speed in the XL RG...if I have about an 80kt tailwind!!!  I
>> too am going thru the "I tired of freezing to death and I'm not going to
>> take it any more."  I'm going to try tapping into the oil line to the
> front
>> cooler and route it to a cooler in a plenum in the nose so the air flow
> can
>> slow down and absorb the heat or I'll route it to a oil cooler in the
> cabin
>> and use a fan to blow air across it.
>> 
>> No doubt about it, the heated seats and nice blanket doesn't cut it at
> -8C.
>> It feels like a meat locker.  When I blocked off enough air flow through
> the
>> front oil cooler, it heated up the air nice, but the engine oil temp went
> up
>> 30F.  I don't know what I'm doing, but I'm doing it!!!
>> 
>> Want a cheap speed increase...gap seals were the answer for me.  I gained
> an
>> easy 5 kts and maybe as much as 8-9kts with a $5 gap seal kit, though it
>> doesn't help aileron responsiveness any!
>> 
>> Chuck
>> 
>> -----Original Message-----
>> From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
>> Behalf Of Jack Sheehan
>> Sent: Monday, January 26, 2004 2:03 PM
>> To: reflector@tvbf.org
>> Subject: Re: REFLECTOR: Vortilons
>> 
>> Wow ! So much discussion VG's Vortillons , Trailing edge fences. I
>> must be nuts. I have about 150 Hours on my XL-RG I did the test
>> flying without anything. It flew great. I painted the airplane and it
>> flew better. ( guess I just got better). I have looked at all the
>> stuff and am reluctant to make any changes because the wing just
>> looks good clean. The airplane gets a little sloppy below 100 knots
>> with the gear down. You have to use the rudders to lead the turn and
>> the aileron inputs are very deliberate. The problem I have is I am so
>> used to it everything feels OK. I plan to install the vortillons and
>> see if that makes a big change and then put on some trailing edge
>> fences to see if that does anything. I would remove anything that
>> effects the top end. I would rather go fast.
>> The only other modification I would be looking to do would be to get
>> some more heat in the airplane. On a trip back from Kentucky last
>> week I was really cold OAT -8C @  FL 015 but the ground speed was 260
>> KTS 285 in the decent.
>> Jack
>> N55XL
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> 
> --
> Jim Sower ... Destiny's Plaything
> Crossville, TN; Chapter 5
> Long-EZ N83RT, Velocity N4095T
> 
> 
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